What’s inside America’s banks?

But an even bigger problem has developed—one that more fundamentally threatens the safety of the financial system—and it more squarely involves the sort of big investors with whom Holmes spends much of his time. More and more, the people in the know don’t trust big banks either.

A chief executive of one of the nation’s largest financial institutions told us that he regularly hears from investors that the banks are “uninvestable,” a Wall Street neologism for “untouchable.”

That’s an increasingly widespread view among the most sophisticated leaders in investing circles. Paul Singer, who runs the influential investment fund Elliott Associates, wrote to his partners this summer, “There is no major financial institution today whose financial statements provide a meaningful clue” about its risks. Arthur Levitt, the former chairman of the SEC, lamented to us in November that none of the post-2008 remedies has “significantly diminished the likelihood of financial crises.” In a recent conversation, a prominent former regulator expressed concerns about the hidden risks that banks might still be carrying, comparing the big banks to Enron.

A recent survey by Barclays Capital found that more than half of institutional investors did not trust how banks measure the riskiness of their assets. When hedge-fund managers were asked how trustworthy they find “risk weightings”—the numbers that banks use to calculate how much capital they should set aside as a safety cushion in case of a business downturn—about 60 percent of those managers answered 1 or 2 on a five-point scale, with 1 being “not trustworthy at all.” None of them gave banks a 5.

A disturbing number of former bankers have recently declared that the banking industry is broken (this newfound clarity typically follows their passage from financial titan to rich retiree). Herbert Allison, the ex-president of Merrill Lynch and former head of the Obama administration’s Troubled Asset Relief Program, wrote a scathing e-book about the failures of the large banks, stopping just short of labeling them all vampire squids. A parade of former high-ranking executives has called for bank breakups, tighter regulation, or a return to the Depression-era Glass-Steagall law, which separated commercial banking from investment banking. Among them: Philip Purcell (ex-CEO of Morgan Stanley Dean Witter), Sallie Krawcheck (ex-CFO of Citigroup), David Komansky (ex-CEO of Merrill Lynch), and John Reed (former coâ€‘CEO of Citigroup). Sandy Weill, another ex-CEO of Citigroup, who built a career on financial megamergers, did a stunning about-face this summer, advising, with breathtaking chutzpah, that the banks should now be broken up.